Trans-Fatty Acids is the scariest word(s) that you can utter, these days! As the awareness spreads, most of the brands are quick to claim proudly on their products on the shelves in supermarkets, that there are “Zero Trans fats” in their products, along with many other claims!
Unsaturated (mono or poly) fatty acids have one or more double bonds, around which carbon and hydrogen atoms are attached. The arrangement of carbon atoms around the double bond can be on the same side (cis-) or opposite side (trans-), and this gives rise to the name – Trans fatty acid.
Unsaturated fatty acids, by their very definition have lesser number of hydrogen atoms, and hence can be subjected to a process called hydrogenation. When the hydrogenation process is complete, it gives us saturated fatty acid chains, but if it is only partially complete, it gives rise to Trans fatty acid chains. Thus, essentially oils from plant sources were used, since they are naturally unsaturated.
The resultant product of partial hydrogenation is a soft, malleable butter like substance (called margarine), which had some special properties like it remained soft even when refrigerated, had a longer shelf life and more. It was also cheaper than butter, since vegetable oils are more readily available than those from animal sources and also could be mass produced easily. It was found especially beneficial for the process of baking and also resulted in enhancing the taste of the products. Thus, partially hydrogenated vegetable oil was a common ingredient on all baked products like cakes, biscuits, breads etc. until recently, apart from widespread use for frying etc. in many restaurants, food outlets etc.
TFAs have no role in promoting health. In fact they have a serious disadvantage over saturated and unsaturated fatty acids in that, they lower the levels of HDL (good) cholesterol in the body apart from increasing LDL levels. The others only increase levels of LDL (bad) cholesterols! Thus they have a more serious negative effect on health and increase chances of coronary heart diseases, lifestyle disorders and more!